The use of radar to produce interferometry maps for identifying movement in a slope is known. U.S. Pat. No. 6,850,183 describes a slope monitoring system that consists of a radar module that records radar images of a selected slope and a video module that records visual images of the same slope. A data processor performs coordinate registration to align the radar images and the visual images. Slope movement is detected by interferometry. The invention is embodied in a product produced by GroundProbe Pty Ltd that is referred to as the SSR.
The SSR product has been used very successfully to monitor the stability of large slopes in open-cut mines. The SSR has detected and provided an alarm prior to many hundreds of large slope failures and is widely recognised as an essential mine safety tool. Nonetheless, the SSR is not ideal for all situations.
Mine workers are exposed to a number of major hazards including sudden or unexpected movement of ground in their immediate work area. Mine workers are not equipped with the knowledge or tools to understand whether a wall that they are planning to work under is and remains safe. SSR is used by mine geotechnical engineers to assess overall slope stability over an extended period, typically days or weeks, and to critically monitor slopes that are actively moving and may become unsafe. The complexity of SSR allows for geotechnical engineers to assess movement types and movement rates across multiple work areas of a mine from long ranges, with alarm capability to a central location. However there are specific work areas in a mine that are not adequately covered or alarmed by SSR. What is required is a simple short-range, fast-scanning tool that can be operated directly by a work crew and can provide a local alarm with sufficient warning when a movement occurs within the work area.